The present invention relates to a test fixture for integrated circuits.
Microelectronic integrated circuit (IC) device fabrication technologies have focused its design techniques and materials to produce smaller and faster operating devices with greater functionaries and a higher culmination of I/O numbers; corresponding to a compact finite accruement comprising a terminal pitch. This trend towards miniaturization has led to demand for improved semiconductor contactors (fixtures) and interconnect performance. On center architectures of fixturing are typically targeted to (BGA) ball grid array, (LGA) land grid array, and dual row (QFN) quad flat no lead, etc., market segment package types with dense order formations. Pogo pin technologies and other linear practical design techniques establish a temporary connection between the (DUT) device under test and the load board or (PCB) printed circuit board. The characteristic contact condition and mechanism of these recognized standard designs is the sole coercion of compliancy distinctly supplying a force to penetrate through DUT lead oxides or residue without accumulation or embedment of debris in order to deliver an uncontaminated interface through the means of contact pressure to achieve low and stable contact resistance followed by consecutive recurring touchdowns with each DUT. The operative function for electronic junction of the DUT typical for on center architectures widely practiced, i.e., spring pins, fuzz-button hardhat, permeated conductive elastomer, flex particle interconnect, or conductive epoxy bump primarily rely on dynamics of contact penetration or dent exclusive acts. This contestable lone nature of electrical contact operation combined with the various sharp crown tips on most spring probes' prior art to provide repeatable, positive contact to the DUT terminal is organic contamination, particle debris, and surface film trace element permeation of the crown tips' service that can lead to high contact resistance, false contact failure rejects, and raise frequent spring probe tip cleaning intervals ceding to test down time; equating to profitable loss proportions in semiconductor production test facilities. Another common class of contactor offers an oblique connection or offset structure amongst the DUT terminal and PC board providing contact pin compliance along with an amount of translation conduct on the DUT terminal surface. It is believed that those skilled in the art have tolerated or neglected to fully appreciate the potential adverse effects on performance and reliability issues arising with the emergence of this technique constituting the collateral launch or branch from the load board to the contactor.
The required size and location for the contactors' recipient PCB pads may affect the capacitance on the surface of the load board. Related to the DUT frequency of interest, load board compensations are likely to be addressed elsewhere in order to optimize signal integrity for this type of interface.
Accordingly, prior methods of testing IC's including many prior art reduced scale sockets that exert self-part contact embodied treatments thataway bend, distort, deflect, or twist allowing for vectorial compressive forces that are prone to soften or rupture over repeatedly burdened motions of self-activity and are likewise not aftereffect suitable for all package and contact types, and pose greater reliability challenges as I/O counts both grow and the spacing between external contacts decreases.
It is therefore a first object of the present invention to provide a stable, repeatable electrical contact through the use of coincident compliance coupled with lateral directional movement(s) to the DUT terminal to break through oxides, emulsion, residue, and mold release film.
Another object of the invention is to provide sufficient contact (contacts) with less force, thus preservation to the DUT pad/ball surface minimizing alteration or deformation.
Yet an additional object of the invention is to provide increased testing accuracy, reliability and minimize the need for retest.
Others objective of the invention are to minimize the potential for device/IC damage, among them die-cracking of the product under test, to provide longer test fixture cycle life, decreases cost of ownership, longer mean time between assists or repair, improves test yields, provide the flexibility to work with different package types and scale formats including (BGA and LGA with high I/O counts)
Summary of Invention
In the present invention, the various objectives are generally achieved by providing test module comprising a dielectric housing with a plurality of cavities, a forked regulator disposed in at least a portion of the plurality of cavities and having a base and a pair of arms extending upward from the base, at least one transversal disposed in rotary engagement within said forked regulator and having; a rounded basal region for permitting rotary motion within the regulator, and an armature extending upward from the basal region for making a signal transmitting contact with the external terminal of a DUT, and means for rotary movement of the transversal basal region in the regulator whereby an electrical contact impinging vertically on the armature results in the vertical and then horizontal movement thereof with respect to the initial point of contact therewith.
In the present invention, the various objectives are generally achieved by providing test module (a test module) for supporting and making electrical contact and external signal connection to a device under test (DUT) having a plurality of external terminals, the test module comprising a generally planar dielectric housing having an upper surface, a lower surface and a plurality of cavities that extend generally vertically from the upper surface to the lower surface, a forked regulator disposed in at least a portion of the plurality of cavities and having a base and a pair of arms that extend upward from the base, at least one transversal disposed in rotary engagement within said forked regulator and having; a rounded basal region for permitting rotary motion within the regulator, and a curved armature extending upward from the basal region beyond the pair of arms of the forked regulator and terminating in an upper appendage having an upward facing surface for making a signal transmitting contact with external terminals of a DUT, means for rotary movement of the basal region of the transversal within said forked regulator whereby an external terminal of a DUT impinging vertically on the upper appendage results in the vertical and then horizontal movement in a first lateral direction thereof with respect to an initial point of contact of the external terminal of the DUT
In another more preferred embodiment of the invention, the forked regulator and the transversal of the test module are electrically conductive and make multiple point of contact with each other when the external terminal of the
DUT are urged vertically downward on the test fixture such that the upper appendage thereof first undergoes a vertically downward displacement and then horizontal movement in a first lateral direction thereof with respect to an initial point of contact with the external terminal of the DUT.
In another more preferred embodiment of the invention, the test module further comprises a second transversal disposed in rotary engagement within said forked regulator and having; a rounded basal region for permitting rotary motion within the regulator, and a curved armature extending upward from the basal region beyond the pair of arms of the regulator and terminating in an upper appendage having an upward facing surface for making signal transmitting contact with the same external terminals of the DUT as the first transversal, wherein each transversal undergoes rotary movement in the opposite direction of the other transversal within the region of the regulator between the base and the pair of arms that extend upward from the base.
The above and other objects, effects, features, and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.